Apparatus for drying batches of disks

ABSTRACT

Liquid is removed from batches of substrates by apparatus and methods for drying substrates that have been wet in an elongated liquid bath. The substrates are moved relative to the bath and an elongated gas-filled volume at rates of movement selected according to the location of the batches of substrates in the bath or the volume. As an example, the substrates and the bath are separated at a controlled rate to form a thin layer of liquid on each substrate as each substrate enters the gas-filled volume. The gas-filled volume is defined by an elongated hot chamber and hot gas directed into the volume and across the substrates and out of the volume continuously transfers thermal energy to the substrates . The flow rate of the gas into the volume is related to introduction of the substrates into the bath to avoid disturbing the liquid in the bath. The thermal energy transferred to the substrates in the volume evaporates the thin layer from the substrates without decreasing the rate of separation of the substrates and the bath below the maximum rate of such separation at which a meniscus will form between the bath and the surface of one of the substrates during such separation. Relative humidity in the volume is controlled by sensing the relative humidity and regulating the speed of a fan that draws gas from the volume.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority from U.S. Provisional PatentApplication No. 60/136,635 filed May 27, 1999, and entitled “NextGeneration Modular Disk Cleaning System Including Transfer, Immersion,Cascade Brush Scrubber and Dryer Assemblies”. This ProvisionalApplication is herein incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to removing liquid fromsubstrates, and more particularly to apparatus and methods for dryingbatches of substrates that have been wet in a liquid bath, after whichthe batches of substrates and the bath are separated at a controlledrate to form a thin layer of liquid on each substrate of the batches asthe batches of substrates are positioned in a gas-filled volume, whereinthe volume is defined by an elongated hot chamber that continuouslytransfers thermal energy to the batches of substrates in the volume, andwherein curtains of hot gas directed into the volume and across thebatches of substrates and out of the volume continuously transferthermal energy to the batches of substrates, so that the thermal energytransferred to the batches of substrates in the volume evaporates thethin layer from each of the substrates without decreasing the rate ofseparation of the batches of substrates and the bath below a maximumrate of such separation at which a meniscus will form between the bathand the surface of each substrate during such separation.

2. Description of the Related Art

In the manufacture of semiconductor devices, process chambers areinterfaced to permit transfer of substrates (such as semiconductorwafers of any of various sizes) between the interfaced chambers. Suchtransfer is via transport modules that move the substrates, for example,through slots or ports that are provided in the adjacent walls of theinterfaced chambers. For example, transport modules are generally usedin conjunction with a variety of substrate processing modules, which mayinclude semiconductor etching systems, material deposition systems, flatpanel display etching systems, and substrate cleaning systems. Due togrowing demands for cleanliness and high processing precision, there hasbeen a greater need to reduce the amount of human interaction during,between, and after such processing steps. This need has been partiallymet with the implementation of vacuum transport modules which operate asan intermediate substrate handling apparatus (typically maintained at areduced pressure, e.g., vacuum conditions). By way of example, a vacuumtransport module may be physically located between one or more cleanroom storage facilities where substrates are stored, and multiplesubstrate processing modules where the substrate are actually processed,e.g., etched or have deposition performed thereon, or cleaned. In thismanner, when a substrate is required for processing, a robot arm locatedwithin the transport module may be employed to retrieve a selectedsubstrate from storage and place it into one of the multiple processingmodules.

Despite use of such intermediate substrate handling apparatus, it isstill necessary to clean and dry the substrate at the completion of suchprocessing. As an example, after the substrate have been cleaned, thesubstrate may have a non-uniform coating of liquid. A substrate withsuch non-uniform coating of liquid, or with one or more drops of liquidthereon, or with any liquid thereon in any physical form, may be said tobe “wet”. In contrast, a substrate having a uniform coating of liquidmay be said to be “uniformly wet”.

In the past, substrates such as annular-shaped disks of many varioussizes have been used for manufacturing data storage devices, forexample. Such substrates have also been subjected to a drying operation.After cleaning and while wet, such substrates have been placed in a tankcontaining a bath of hot liquid. In one type of drying operation, thehot liquid has been drained from the tank at a rate such that a thinlayer of liquid, rather than one or more drops of liquid, forms on thatportion of such substrate that is out of the draining liquid. The thinlayer has been preferred over one or more drops because a drop of liquidhas a high volume, e.g., from about 0.001 ml. to about 0.020 ml. Incomparison to the drop, a thin layer of liquid on a substrate such as a95 mm diameter disk, may only have a volume of at the maximum diameterof the disk of about 0.0007 ml, for example. Evaporation of a dropgenerally results in the concentration of small particles at the lastsmall point on the disk at which the drop exists. When the substrate isa wafer, such concentration may result in defects in a chip made fromthe wafer.

To remove the thin layer from such substrate, reliance has been placedon the thermal energy stored in such substrate to provide the thermalenergy necessary to evaporate the thin layer. However, when suchsubstrate is a “wafer”, as defined above, problems have been experiencedin not properly drying the thin layer from the wafer. For example, itappears that using only such stored thermal energy, the thin layerevaporates from the wafer at a rate less than the maximum rate ofseparation of the liquid bath and the wafer at which a meniscus willform between the liquid bath and the surface of the wafer during suchseparation. Thus, the rate at which the liquid is drained from the tankhas to be decreased to match the rate of evaporation. Alternatively, thewafer would have to be retained in the tank after the draining has beencompleted. Each of such decreased rate of draining and such retainingincreases the time required to dry the wafer, which increases the costof fabricating devices based on the wafer.

Additionally, when the substrate is a disk that is used to manufacturegenerally low-cost data storage devices, for example, it is necessary toprocess large numbers of such substrates at the same time. However,difficulties have been experienced in assuring uniform drying of each ofsuch substrates. As an example, if the flow rate of the hot gas into thevolume is increased in an attempt to process a large number ofsubstrates, the higher flow rate gas may disturb the surface of theliquid bath, resulting in splashing of the liquid onto the surfaces ofthe substrates. Such splashing may form drops on one or more of thesurfaces. Also, even when more than one substrate is processed at thesame time, use of a uniform rate of movement of the substrates into,within, and out of the liquid result in inefficiencies, such asrelatively long periods of time of a drying cycle. In addition, whenmore than one substrate is processed at the same time relative humidityproblems within the gas volume affect processing of more than onesubstrate at a time.

In view of the forgoing, what is needed is apparatus and methods ofefficiently drying substrates. Such efficient drying should allowbatches of the substrates to be efficiently processed. Such efficientdrying should also allow the rate of movement of the batches of thesubstrates to be controlled according to the nature of the movement,e.g., entry of the substrates into the liquid, or movement of thesubstrates from a deep immersion position to a shallow immersionposition in the liquid, or suspense of movement of the substrates, forexample. Such control should also allow the liquid and the substrates tobe separated at a rate no less than the maximum rate of separation ofthe liquid and the substrates at which a meniscus will form between theliquid bath and the surface of the substrate. In addition, the efficientdrying should assure that the upper surface of the liquid is smoothduring such separation. Further, the efficient drying should minimizethe effect of relative humidity on the drying of batches of thesubstrates. Also, the efficient drying should very rapidly remove fromthe substrate a thin layer of liquid that forms on the substrate as thesubstrate and the bath are separated, wherein “rapidly” means suchremoval occurs before the substrate and the bath have been completelyseparated e.g., separated by 0.004 inches, for example.

SUMMARY OF THE INVENTION

Broadly speaking, the present invention fills these needs by providingapparatus and methods of efficiently removing fluid from batches ofsubstrates. The efficient removing is attained by providing apparatusand methods for drying batches of substrates that have been uniformlywet in a fluid bath. Such efficient drying is enhanced by controllingthe rate of movement of the batches of the substrates according to thenature of the movement, e.g., entry of the substrates into the liquid,or movement of the substrates from the deep immersion position to ashallow immersion position in the liquid, or suspense of movement of thesubstrates, for example. As another example, the batches of substratesand the bath are separated at a controlled rate to form a thin layer offluid on each of the substrates in the batches as each of the substratesis positioned in an elongated gas-filled volume. In addition to suchseparation, the efficient removing is attained by defining thegas-filled volume by use of an elongated hot chamber and curved gasinlet manifolds that form an elongated curtain of hot gas that transfersthermal energy to the batch of substrates in the volume. Further, duringa drying cycle, the elongated curtain of hot gas is continuouslydirected into the volume and across each substrate of the batch ofsubstrates and out of the volume to continuously transfer thermal energyto the wafer. While the directing of the gas out of the volume isindependent of the separation of the bath and the substrates, the rateof gas flow into the volume is decreased during entry of the batches ofthe substrates into the volume. In addition, conditions are controlledso that the upper surface of the fluid is smooth during such separation.The thermal energy transferred to the batches of substrates in the bathand in the volume very rapidly evaporates the thin layer from the waferwithout decreasing the rate of separation of the batches of substratesand the bath below the maximum rate of such separation at which ameniscus will form between the bath and the surface of the substratesduring such separation. The effect of relative humidity in promotingrecondensation of liquid vapor onto the dried substrates of the batchesis avoided by providing an exhaust fan to draw the liquid vapor-ladengas from the volume at a location away from the elongated hot chamber.

Such efficient removal enables the substrate throughput of suchapparatus and method to be limited only by the type of substrate that isbeing dried, and the type of liquid used to wet the substrate. Forexample, the characteristics of particular types of substrates andliquid dictate the maximum rate of such separation of the substrate andthe bath at which a meniscus will form between the bath and the surfaceof the substrate during such separation, and at which the substrate willbe uniformly wet.

In one embodiment of the present invention, a system for drying batchesof substrates is provided with an elongated bath enclosure configured tohold fluid. The fluid defines a top fluid surface and the elongated bathenclosure has an upper end defined by a weir having a saw-toothedconfiguration. A temperature and humidity-controlled chamber is definedabove the upper end, the chamber being elongated corresponding to theelongation of the elongated bath and having opposing long walls. Thechamber has a series of first openings along the long walls at a firstlocation adjacent to the upper end and opposed second openings at asecond location that is spaced from the upper end.

In one aspect of the one embodiment of the present invention, a systemfor drying batches of substrates is provided for substrates havingopposite planar sides that are parallel to a planar axis. A substratetransport unit immerses a plurality of batches of substrates in thefluid with the planar axis of each substrate generally perpendicular tothe fluid surface and the opposite planar sides of each substrategenerally perpendicular to the long walls. A drive is provided forcausing the substrate transport unit to move the batches of substrateswithin and out of the fluid with the planar axis remaining generallyperpendicular to the fluid surface. The drive controls the rate ofmovement of the batches of substrates according to the location of thebatches of substrates within and out of the fluid.

In another aspect of the one embodiment of the present invention, acontroller is provided to control operation of the drive tosimultaneously move the batches of substrates at rates of movementcontrolled according to the location of the batches of substrates withinand out of the fluid.

In a next embodiment of the present invention, apparatus is provided fordrying a plurality of batches of substrates, wherein each of thesubstrates has opposite sides. A bath is adapted to contain hot liquid,and the liquid defines an upper liquid surface. The bath is elongated tosimultaneously receive the plurality of batches of substrates aligned inseries along a batch substrate path. The bath has a saw toothed weirdefining an upper end of the bath over which the liquid may flow out ofthe bath. A liquid collection tank surrounds and supports the bath forreceiving the liquid flowing over the weir, and the tank has an upperend above the weir. A drain system is connected to the tank forrecirculating the liquid that flowed over the weir. The drain systemheats, filters, and returns the liquid to the bath. An enclosure isconfigured to receive the plurality of batches of substrates aligned inseries along the batch substrate path. The enclosure has opposingelongated walls positioned on opposite sides of the batch substratepath. Also, the enclosure has an upper end and a base spaced from theupper end, the walls being connected to the tank for supporting the tankand the bath. A series of gas inlets is defined in each of the opposingelongated walls at the upper end of the enclosure and spaced from theweir. The inlets extend along the opposing elongated walls on oppositesides of an upper position of the batch substrate path. A gas outletadjacent to the base of each of the elongated walls is spaced from theupper liquid surface. The enclosure and the inlets and the outletsdefine continuous gas flow paths from the inlets through the enclosureto the outlets, the flow path extending across the weir for drawingambient vapor from the bath directly to the outlets.

In another aspect of the next embodiment of the present invention, thesubstrates each have a narrow edge between the sides and the carrier haselongated spaced arms configured to extend in the enclosure parallel toand between the opposing elongated walls. A substrate batch nestcorresponds to each batch of the substrates. Each nest includes aplurality of spaced bars and spaced end plates mounting the bars on thespaced arms. Each of the bars includes a vertical surface intersecting athree-dimensional V-shaped notch that corresponds to each substrate tobe carried. Each V-shaped notch is formed in the bar with a valley andopposite walls extending at an acute angle with respect to the verticalsurface. The vertical surface and the acute angle of the V-shaped notchcombine to limit the contact between the substrate and each V-shapednotch. The contact is a substantially point contact between one of theopposite walls of the notch and one end of the narrow edge of thesubstrate.

In a further embodiment of the present invention, apparatus is providedfor drying a plurality of batches of substrates. There is a relativelyshort wall at each end of the opposing elongated walls. The upper end ofthe enclosure is provided with an elongated opening defined by theopposing elongated walls and by the relatively short walls. Theelongated opening is configured to receive the plurality of batches ofsubstrates aligned in the series along the batch substrate path. Aplurality of doors is provided, each door having first ends adjacent toone of the short walls and opposite second ends adjacent to the other ofthe short ends. Door mounts are adjacent to each of the short walls forguiding the doors across the elongated opening in opposition to eachother. A drive is mounted adjacent to one of the short walls andconnected to the first end of one of the doors. A first endless belt isdriven by the drive and is connected to the corresponding first end ofthe other of the doors so that the corresponding first ends of the doorsmove simultaneously on the door mounts. A connecting shaft is providedfor each of the doors. The shafts are driven by the first endless beltand extend from the one of the short walls to the other of the shortwalls. A second endless belt driven by the connecting shafts moves theopposite corresponding second ends of the doors simultaneously and insynchronism with the movement of the corresponding first ends of thedoors to open or close the elongated opening.

In a method embodiment of the present invention, drying a substrateincludes an operation of simultaneously immersing a plurality of batchesof substrates into a bath of hot liquid having a given depth extendingfrom a liquid surface to a bottom of the bath. The immersing operationpositions the batches of substrates at a deep immersion locationadjacent to the bottom. The substrates are retained at the deepimmersion location for a predetermined period of time. After thepredetermined period of time, there is an operation of quicklytransiting the batches of substrates from the deep immersion location toa shallow immersion location adjacent to the liquid surface. A furtheroperation pulls the batches of substrates out of the liquid from theshallow immersion location to dry the batches of substrates.

Other aspects and advantages of the invention will become apparent fromthe following detailed description, taken in conjunction with theaccompanying drawings, illustrating by way of example the principles ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be readily understood by the followingdetailed description in conjunction with the accompanying drawings, inwhich like reference numerals designate like structural elements.

FIG. 1A depicts an apparatus for moving batches of substrates held inseparate carriers (or nests) for drying the batches of substratesaccording to the present invention.

FIGS. 1B and 1C respectively depict a substrate in the form of anannular-shaped disk for memory applications, and a substrate in the formof a wafer for semiconductor device manufacture.

FIG. 2 depicts a perspective view of an apparatus for drying the batchesof substrates according to the present invention, wherein an elongatedset of doors allow access to an elongated gas-filled chamber providedabove a bath for heated liquid.

FIG. 3 is an end elevational view of the apparatus shown in FIG. 2,illustrating gas inlets on opposite sides of the elongated gas-filledchamber and gas outlets provided above the bath.

FIG. 4 is a side elevational view of the apparatus shown in FIGS. 2 and3, illustrating the bath having a saw toothed weir and a drain tanksurrounding the bath for receiving liquid from the bath.

FIGS. 5A and 5B depict a perspective views of a first end of theapparatus for drying the batches of substrates according to the presentinvention, wherein a drive having one motor shown in FIG. 5A moves acorresponding first end of the elongated set of doors on a guide rodshown in FIG. 5B in synchronism to open or close the chamber.

FIG. 6A is an end view of the first end of the drive, showing a singlepneumatic motor that directly moves one of the doors, and a belt drivenby the motor for moving the other of the doors.

FIG. 6B is a cross sectional view of one pulley for the endless belt,showing one of two shafts for moving a corresponding second opposite endof the elongated set of doors in synchronism with movement of the firstend.

FIG. 6C is a cross sectional view of a shaft for guiding the movement ofthe first end of the doors, showing one of the doors connected to onelength of the belt.

FIG. 6D is a cross sectional view of the shaft for guiding the movementof the first end of the doors, showing a second of the doors connectedto an opposite length of the belt.

FIG. 7 is an enlarged cross sectional view of the connection between thechamber and the tank, showing the tank supported by the chamber andsupporting the bath.

FIG. 8 is a schematic view of a gas supply subsystem for feeding hot gasto gas inlets of opposite sides of the chamber.

FIG. 9A is a plan view of one of the gas inlets showing a curvedconfiguration of a diffuser for laterally spreading the gas receivedfrom an inlet pipe.

FIG. 9B is a cross sectional view taken along line 9B—9B in FIG. 9A,showing one end of the gas inlet.

FIG. 9C is a cross sectional view taken along line 9C—9C in FIG. 9A,showing the center of the gas inlet.

FIG. 9D is a schematic elevational view showing gas curtains flowingbetween the substrates in the chamber.

FIG. 10 is a perspective view of one of the carriers shown in FIG. 1,depicting spaced bars configured to contact each substrate of thebatches of substrates, wherein such contact is limited.

FIG. 11A is a cross sectional view of one of the bars of the carrier,showing a thin upper section having spaced vertical surfaces that arecut by V-shaped notches that define a nest for a substrate.

FIG. 11B is a cross sectional view taken along line 11B—11B in FIG. 11A,showing the V-shaped notches.

FIG. 11C is an enlarged view taken along line 11C—11C in FIG. 11A,showing a substrate nested in one V-shaped notch, illustrating onesubstantially point of contact between a thin end of the substrate andone of two opposite walls of the V-shaped notch.

FIG. 12 is a schematic view of the side of the apparatus for drying thebatches of substrates, illustrating a drive for moving an arm thatcarries the carriers, wherein the positions of the carriers arecontrolled by a controller.

FIG. 13 is a schematic diagram of a control circuit that supplies datato the controller for synchronizing the various operations of theapparatus.

FIG. 14 depicts a flow chart showing operations of a first method forsimultaneously drying a plurality of batches of substrates.

FIGS. 15A through 15D are schematic views of an end of the apparatus,showing various positions of one of the carriers and the batch ofsubstrates in that carrier.

FIG. 16A is a schematic diagram of the surface of a substrate during thepull operation, illustrating a meniscus and a thin film.

FIG. 16B is a schematic diagram of an end view of a substrate during thepull operation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An invention is described for drying batches of substrates. Theinvention is described in terms of apparatus for and methods ofefficiently removing liquid from the substrates. More particularly, theinvention is described in respect to apparatus and methods for removingliquid from batches of substrates to dry the substrates after thebatches of substrates have been wet in a liquid bath. The removing ofthe liquid is initiated as the substrates and the bath are separated ata controlled rate to uniformly wet the substrates, i.e. to form thinlayers of liquid on portions of a substrate just as the portions leavethe bath and enter a hot-gas-filled volume defined by a hot chamber. Thehot chamber and the hot gas continuously transfer thermal energy to thesubstrates and the thin layers in the volume. The removing of the liquidis rapidly completed as the substrates enter the volume in that thethermal energy transferred to the substrates and to the thin layer veryrapidly evaporates the thin layers from the substrates. The evaporationis at a high enough rate such that there is no decrease in the rate ofseparation of the substrates and the bath below the maximum rate of suchseparation at which a meniscus will form between the bath and thesurface of the substrates during such separation. Additionally, therelative humidity in the hot-gasfilled volume is controlled to inhibitrecondensation of vapor from the bath. It will be obvious, however, toone skilled in the art, that the present invention may be practicedwithout some or all of these specific details. In other instances, wellknown process operations have not been described in detail in order notto obscure the present invention.

FIG. 1A depicts an apparatus 100 for moving batches 102 of substrates104 held in separate carriers 106 for drying the batches 102 ofsubstrates 104 according to the present invention. According to thesize, for example, of the substrates 104, there may be many substrates104 in a batch 102. The batches 102 of substrates 104 depicted in theFigures may include twenty-five substrates 104 per batch 102, forexample. However, other numbers of substrates 102 may be provided in abatch 102. Each batch 102 is carried by one of the separate carriers106, which are also referred to as nests.

FIG. 1A shows an exemplary four nests 106, and thus four batches 102 ofsubstrates 104, aligned on a horizontal substrate drying axis 108. Apair of spaced elongated nest fingers 110 (partially shown in dashedlines) is mounted on a bifurcated horizontal arm 112 cantilevered from amain batch drive column 114. The fingers 110 support the nests 106. Thearm 112 and the fingers 110 have a length LC sufficient to carry fourexemplary nests 106, although other numbers of nests 106 and lengths LCmay be provided according to the desired substrate throughput. The maindrive column 114 is mounted for vertical movement along a vertical axis116, and moves the spaced arms 112 up and down to move the batches 102of substrates 104 during substrate drying operations.

FIG. 1B shows that the substrates 104 may be annular-shaped disks 120having a central aperture 122. The disks 120 may be of any of varioussizes, e.g., 65 or 95 mm. in diameter, and may be fabricated from glassor aluminum, e.g., for applications such as for manufacturing datastorage devices (not shown), for example. Such disks 120 have oppositeplanar sides 124 parallel to a disk axis 126. The sides 124 areseparated by a thin edge 128. Because there is generally no edgeexclusion on a disk 120 (typically five mm.), the entire annular area ofsuch disk 120 is generally used, such that care must be taken toproperly dry such entire area. Such care includes minimizing the surfacearea of the disk 120 that is touched in supporting the disk during thedrying operation. By using adequate care according to the presentinvention, one may avoid having so-called “mouse-ears” (not shown) format the junction of the edge 128 and the side 124 of the disk 120.Mouse-ears are formed, for example, when de-ionized water dries at aspot on the side 124 near the edge 128 of the disk 120. Suchannular-shaped disks 120 for data storage devices and similarapplications are referred to below as “disks”, and are included withinthe term “substrates”.

FIG. 1C shows that the substrates 104 may also be circular-shaped andhave any of various sizes, such as 200 mm. or 300 mm. in diameter. Suchsubstrates 104 are known as “wafers” 130, may be made from semiconductormaterial, and are used for manufacturing semiconductor chips (notshown), for example. Such wafers 130 have opposite planar sides 132parallel to a wafer axis 134. The sides 132 are separated by a thin edge136. Although there generally is an edge exclusion on a wafer 130 (andthus not all of the entire circular area of such wafers 130 is used),care must still be taken to properly dry the entire circular area. Forexample, because mouse-ears may be relatively large and extend beyondthe edge exclusion, one must still exert adequate care, such as byminimizing the surface area of the wafer 130 that is touched to supportthe wafer 130 during the drying operations. Such circular-shaped wafers130 for semiconductor device manufacture and similar applications arereferred to below as “wafers”, and are included within the term“substrates” as used below.

FIG. 2 depicts the apparatus 100 for drying batches 102 of thesubstrates 104 according to the present invention. The elongated arms112 lower the plurality of carriers 106, with the batches 102 ofsubstrates 104 thereon, between open elongated opposing doors 140 thatare movably mounted at the top 142 of a chamber 144. Below the doors 140an elongated temperature and humidity-controlled chamber 144 is definedand receives the batches 102 of substrates 104. The elongation of thechamber 144 corresponds to the length LC of the arms 112. The chamber144 is defined by opposed vertical long walls 146 spaced by length L,and opposed short vertical walls 148.

The chamber 144 has a series of first openings (or gas inlets) 150 alongthe long walls 146 at a first, or upper, location 152 adjacent to thetop of the chamber 144. A gas supply system 154 includes a plurality ofpipes 156 extending from a gas main 158 to the gas inlets 150 to supplyheated gas 160 to the chamber 144.

Referring also to FIG. 7, a series of opposed second openings, or gasoutlets 162, is provided at a second, or lower, location 164. Theoutlets 162 extend through an exterior base 166 of each of the longwalls 146. The base 166 coincides with a bottom 168 of the chamber 144.On each side of the base 166, the gas outlets 162 are covered by anelongated exhaust manifold 170 mounted on the base. Each of themanifolds 170 is connected to a plenum 172 that houses a variable speedfan 174 that exhausts the gas 160 and air-borne fluid vapor (see arrows176 in FIG. 7), into an outlet pipe 178 that is connected to the mainexhaust (not shown) of the plant in which the apparatus 100 is housed. Adoor control drive 180 has a separate left section 182 and a rightsection 184 at each respective left end 186 and right end 188 of theapparatus 100. The separate sections 182 and 184 are connected by ashaft 185 to simultaneously apply door motion forces DM to an oppositeleft end 190L and a right end 190R of the doors 140 to open and closethe doors 140, and thus effectively open and close the chamber 144.Except as described below, the separate sections 182 and 184 are thesame.

FIG. 3 shows the nest support fingers 110 positioned by the arm 112below the chamber 144 and in liquid, or fluid 192, contained in anelongated bath, or bath enclosure 194, configured to receive the batches102 of substrates 104. The fluid 192 may be water. Preferably, the water192 is de-ionized. More preferably, the water 192 both de-ionized andfiltered. Most preferably, the water 192 is both de-ionized andfiltered, and heated, before flowing into the bath 194. The fluid 192defines a top fluid surface 196 which may vary in height as describedbelow. The elongated bath enclosure 194 has an upper end 198 defined bya weir 200 having a saw-toothed configuration. The temperature andhumidity-controlled chamber 144 extends above the upper end 198 of thebath 194 and is spaced from the saw toothed weir 200. FIG. 3 also showsthat the bath 194 has a generally U-shaped cross section defined by abottom 202 and elongated walls 204. The weir 200 having the saw-toothedconfiguration is at the top of the walls 204 of the bath 194. Two mainfluid inlets 206 extend through the bottom 202 to supply the fluid 192to the bath 194. The inlets 206 are provided with diffuser plates 208 tospread the incoming fluid 192 laterally across the width W (and lengthL, FIG. 4) of the bath 194.

FIG. 3 also shows the gas supply pipes 156 connected to the gas inlets150, and the gas exhaust manifolds 170 over the gas outlets 162. Thebase 166 of the chamber walls 146 and 148 is connected to a flange 210of a fluid outlet tank 212. The tank 212 surrounds and supports the bath194. FIG. 3 also shows that each of the doors 140 is provided with anotch 214 so that when the main column 114 has lowered the batches 102of substrates 104 into the bath 194, the main column 114 will clear thedoors 140 to permit movement of the main column 114, and the closeddoors 140 may abut and close the chamber 144. The clearance is designedto minimize leakage of the gas 160 from the chamber 144 withoutinterfering with vertical travel of the main column 114.

FIG. 4 shows the elongated chamber 144 and the bath 194, which havecorresponding lengths L sufficient to receive the length LC of the arm112. The tank 212 is shown outside the bath 194 supporting the bath 194.An upper end 216 of the tank 212 is shown above a top level, or open end218, of a standpipe 220 that drains any abnormal overflow of liquid 192from the bath 194. With the liquid 192 continuously supplied to the bath194, the liquid 192 may overflow the weir 200, especially as the bath194 receives the nests 106 and the substrates 104. The normal overflowis drained from the tank 212 by a pair of recirculating drains 222provided at the left end 224 (FIG. 4) of the tank 212. With properoperation of the recirculating drains 222, no flow will be received bythe standpipe 220. FIG. 4 also shows the gas inlets 150 as beingelongated and spaced by short distances to provide and spread theincoming gas 160 across the length L of the chamber 144.

FIGS. 3 and 4 show a system 230 for heating the long walls 146 and theshort walls 148 that define the chamber 144. The system 230 includesflat electrical resistance heaters 232 secured to the sides of the walls146 and 148 opposite to the chamber 144. The heaters 232 are controlledto maintain the temperature of the walls 146 and 148 of the chamber 144at a desired temperature so that thermal energy may be transferred tothe gas 160 to assist in maintaining the gas 160 at a desiredtemperature.

FIGS. 5A, 5B, and 6A through 6D show the one section 182 of the doorcontrol drive 180 at the left end 186 of the apparatus 100 as viewed inFIG. 2. The separate section 182 has a main pneumatic motor 234 thatdrives both sections 182 and 184. The main motor 234 is mounted at afixed location relative to a frame 236 of the apparatus 100 by brackets238. A piston rod 240 is driven by the main motor 234 to move a bentfront plate 242 attached to the front door 140F. The plate 242 is alsosecured to a front force transfer block 244 that rides on one of twodoor guides, or guide rods, 246 that extend from the front to the backof the apparatus 100 as seen in FIG. 2. As the piston rod 240 movestoward the front, the front block 244 is moved toward the front on theguide 246 and correspondingly moves both a front door bracket 248 and alower belt clamp 250 toward the front. The lower clamp 250 is secured toan endless belt 252, and particularly to a lower length, or run 254, ofthe belt 252. The endless belt 252 extends around two spaced pulleys 256and 258, pulley 256 being at the front and pulley 258 being at the rearas seen in FIGS. 2, 5A and 5B. As noted above, sections 182 and 184 arethe same, and the exception is that the shaft 185 and not the motor 234(there is no motor 234 for the section 184), rotates the correspondingfront pulley 256 of right section 184. At right section 184, that frontpulley 256 drives the corresponding belt 252 (not shown), and thestructure and operation are otherwise the same.

Since the lower clamp 250 is driven by the motor 234 through the frontblock 244, the forward motion of the piston rod 240 causes the lowerlength 254 of the belt 252 to travel forwardly and an upper run 260 ofthe belt 252 to move toward the rear. A second, upper belt clamp 262 issecured to, and driven by, the upper run 260 of the belt 252. The upperrun 260 of the belt 252 moves the upper clamp 262 to the rear and movesa second rear-door block 264. The second rear-door block 264 also rideson the guide rod 246. Brackets 266 connected to the rear block 264 mountthe rear door 140R for movement guided by the guide rod 246.

As a result, one motion of the piston rod 240 results in oppositelydirected movements of the doors 140, in this example, to move the doors140 apart and expose an upper opening 268 (FIG. 9D) of the chamber 144.In an opposite example, when the piston rod 240 is driven by the mainmotor 234 toward the rear, the front force transfer block 244 ridestoward the rear on one of the two door guides 246. As the front block244 is moved toward the rear and correspondingly moves the lower beltclamp 250 toward the rear, the lower clamp 250 moves the lower run 254of the belt 252 toward the rear. The rearward motion of the piston rod240 causes the upper run 260 of the belt 252 to move toward the front.As a result, the upper clamp 262 secured to the upper run 260 is movedby the upper run 260 toward the front and moves the second rear-doorblock 264 toward the front. The brackets 266 connected to the rear block264 move the rear door 140R forwardly toward the oppositely(now-rearwardly) moving front door 140F. As a result, the one rearwardmotion of the piston rod 240 results in oppositely directed-movements ofthe doors 140F and 140R, in this example, to move the doors toward eachother and close the upper opening 268 of the chamber 144.

FIG. 7 depicts the bottom 168 of the chamber 144 as having an outwardlyextending chamber flange 270. The chamber flange 270 extends along thelength L of the chamber and is provided with a series of the gas outlets162, each in the form of an aperture 272 shown in FIG. 7. The exhaustmanifold 170 also extends along the length L of the chamber 144 andcollects the gas 160 from the gas outlets 162. The flange 210 of thetank 212 is shown under an outer portion 274 of the chamber flange 270.A gasket 276 (such as PTFE sold under the trademark GORE-TEX), and aseries of bolts 278 sealingly connect the chamber flange 270 to the tankflange 210 so that the tank 212 is supported on the chamber 144.Respective outer and inner walls 280 and 282 of the tank 212 extend fromthe tank flange 210. The inner wall 282 is secured, as by welding, tothe elongated walls 204 of the bath 194 to support the bath.

FIG. 8 shows a plan view of the gas supply system 154 as including thepipes 156 extending from the gas main 158. The pipes 156 branchappropriately to supply the gas 160 to the four gas inlets 150 on eachside of the opening 268 of the chamber 144. For ease of illustration,only the four gas inlets 150 on one side of the chamber 144 are shown inFIG. 8.

Each of the gas inlets 150 has the configuration shown in FIGS. 9Athrough 9C. FIG. 9A shows in plan view a gas inlet 150 elongated in thedirection of the length L (longitudinally) and having a curved rear wall290 also extending generally longitudinally. The last gas supply pipe156 joins the gas inlet 150 from the bottom 292 and as shown in FIG. 9Cdirects the gas 160 against an opposite upper surface 294. The gas flowis directed off the upper surface 294 and the curved rear wall 290 tothe center (see line CL) of the chamber 144 and is also spreadlongitudinally by the curved rear wall 290. As a result, the gas inlets150 on one side of the chamber 144 spread the gas 160 longitudinally andevenly across the length L of the chamber 144.

FIG. 9D shows that the incoming gas 160 from the gas inlets 150 flowsdownwardly within the chamber 144 to define a plurality of gas curtainsGC. The gas curtains GC flow continuously and downwardly adjacent to thecenter CL of the chamber 144 and intersect substrate movement paths 296along which the batches 102 of substrates 104 move in the dryingoperations. Because the substrates 104 are positioned as shown in FIG.1A extending across the chamber 144 from one elongated wall 146 to theopposite elongated wall 146, the gas curtains GC flow from the gasinlets 150, between the adjacent substrates 104 that are carried by oneof the carriers 106, and then out from between the adjacent substrates104 and downwardly. When the substrates 104 are positioned above thebath 194 and in the chamber 144 during and just after being pulled fromthe bath 194, the flow of the gas curtains GC between the adjacentsubstrates 104 assists in evaporating the liquid 192 from the substrates104, and carries the evaporated liquid 192 downwardly in the chamber 144past the substrates 104. FIG. 9D shows that after the gas curtains GCexit the spaces between the adjacent substrates 104, the gas curtains GCinclude the air-bome fluid vapor 176, which is evaporated liquid vaporfrom the substrates 104 (see the arrows 176).

As the batches 102 of substrates 104 are pulled upwardly in the chamber144 out of the liquid 192 and through the chamber 144 toward the topopening 268, the variable speed fan 174 is operated at a speed selectedto produce reduced gas pressure at the base 166 of the elongated chamber144, and specifically reduced pressure downstream of the gas outlets162. As a result of the reduced pressure, after the gas curtains GC(with the vapor 176) exit the spaces between the adjacent substrates104, the gas curtains GC (with the vapor 176) flow away from the centerCL of the chamber 144 and to the gas outlets 162. In this manner, notonly is the evaporated liquid vapor 176 carried with the gas curtainsGC, but any liquid vapor (see dots 298) that is emitted from the bath194 upwardly past the upper end 198 of the weir 200 is carried by thegas curtains GC away from the bottom 168 of the chamber 144 and directlyto the gas outlets 162. As a result, little if any of the liquid vapor298 emitted by the bath 194 will rise above the bottom 168 of thechamber 144. Rather, the primary source of liquid vapor in the chamber144 will be the evaporated liquid vapor 176 that evaporated from theopposite sides of the substrates 104, and such evaporated liquid vapor176 and any liquid vapor 298 both flow with the gas curtains GC directlyto the gas outlets 162 and not up in the chamber 144.

FIG. 10 depicts one of the carriers 106 having a plurality of spacedbars 300 configured for limited contact with each substrate 104. Thebars 300 extend parallel to the length L of the chamber 144. Opposed endplates 302 hold the bars 300 in position to contact the substrates 104.An upper surface 304 of each bar 300 has a generally saw toothconfiguration that defines a series of V-shaped notches 306. Each notch306 is configured to receive and hold a substrate 104 in a verticalposition while making minimal contact with the substrate. In particular,FIG. 11A shows one of the bars 300 as having an enlarged base 308provided with holes 310 for receiving either a pin or a fastener 312(FIG. 10) to secure the bar 300 to the end plates 302. At the top of theenlarged base 308, a thin substrate holder section 314 is shown havingopposite parallel left and right sides 316 and 318 respectively. TheV-shaped notches 306 extend from the left side 316 through the thinsection 314 to the right side 318. FIG. 11A shows that a bottom 320surface of the V-shaped notches 306 is beveled, e.g., is formed at anangle VB relative to vertical. FIG. 11B shows that the “V” of thenotches 306 is formed at an angle VA, half of which is on either side ofvertical. Additionally, a pitch P from one V-shaped notch 306 to theadjacent V-shaped notch 306 is selected according to the thickness ofthe particular substrates. As a result of this configuration and spacing(pitch P) of the V-shaped notches 306, a particular substrate 104 (shownin FIG. 11C as an exemplary disk 120) only touches the notch 306 at twopoints 322A and 322B. The two points 322 are at the left side 316 of thethin section 314. Because the bottom surface 320 of the notches 306 isbeveled (and thus formed at the angle VB with respect to vertical), theportions of the bottom surface 320 and the sides of the notches 306 tothe right of the left side 316 are below the edge (i.e., 128 or 136) ofthe substrate 104 and do not touch the substrate 104. Thus, the angle VAof the notch 306, and the angle VB of the bevel 300 of the bottomsurface 320 of the notch 306 combine to minimize the amount of contactbetween each bar 300 of the carrier 106 and each one of the substrates104, such that only the two points 322A and 322B of each carrier bar 300contact the substrate 104, i.e., only at the left side 316. Further, anyliquid 192 that is on the substrate 104 or on the surface of the thinsubstrate holder section 314 will tend to flow away from the substrate104. In particular, because the left side 316 of the section 314 isvertical, liquid 192 will flow from the left side 316 downwardly ontothe base 308 of the bar 300 and off the bar. Similarly, because of thebevel, or angle VB, of the bottom surface 320 (e.g., sixty degrees fromhorizontal), any liquid 192 that drains from the substrate 104 to theright of the left side 316 will flow down the beveled bottom surface 320and away from the substrate 104. Importantly, because of such verticaland beveled orientations, it is unlikely that the liquid 192 will form apuddle or otherwise accumulate at the points 322A or 322B at which theV-shaped notch 306 and the edge 128 or 136 contact each other, such thatit is very unlikely that a mouse-ear will form on the substrate 104. Itmay be understood that the size of the substrates 104 being dried, e.g.the diameter and thickness, may be taken into consideration indetermining the values of the angles VA and VB, and of the pitch P. Forexemplary substrates 104 in the form of the disks 120 having a thicknessof 0.80 millimeters and a diameter of 95 millimeters, for example, theangle VA may be about one hundred nine degrees, the angle VB may beabout thirty degrees, and the pitch P may be 0.250 inches.

FIG. 12 shows the side of the apparatus 100 for drying the batches 102of substrates 104, illustrating a drive 330 for moving the main column114 and the arm 112 that carries the carriers 106. The drive 330includes a standard servo motor 332 for accurately moving the maincolumn 114 in response to signals 334 from a controller 340 (FIG. 13).The servo motor 332 may be a Model MAC-B231-NF40-C1 unit made by API andhaving (not shown) a lead screw and a servo feedback loop providingsignals 342 to the controller 340. As described in more detail below,the controller 340 causes the servo motor 332 to operate at differentspeeds according to which of many parts of a drying operating cycle isbeing performed.

FIG. 13 is a schematic diagram of a control circuit 343 for controllingthe operation of the system 100. The controller 340 may be aprogrammable controller such as Model No. 2700 controller made by CTC.The controller 340 is shown controlling the operation of the wallheaters 232. Also, the controller 340 provides a control signal 344 to aheater 346 that heats the gas 160 supplied from a gas tank 348. The gastank 348 preferably supplies inert gas 160. More preferably the gas tank348 supplies the nitrogen as the gas 160. Most preferably, the gas tank348 and the heater 346 supply heated nitrogen gas 160 to the inlets 150.A gas curtain temperature sensor 350 is provided in the chamber 144 atabout 0.83 inches above the bottom 168 of the chamber 144. As describedbelow, during the pull of the carrier 106 and the batches 102 ofsubstrates 104 from the fluid 192 there is no re-circulation of thefluid, such that the top fluid surface 196 becomes very smooth, anddrops to about 0.54 inches below the saw tooth top of the weir 200. Withthe gas curtain temperature sensor 350 at the noted location, the gascurtain temperature sensor 350 is in position to accurately monitor thetemperature of the gas curtains GC flowing downwardly to the gas outlets162 during the pull operation. The controller 340 responds to an outputsignal 351 from the sensor 350 and causes the gas heater 346 and thewall heaters 232 to appropriately increase or decrease the thermalenergy provided by each sufficient to maintain the gas curtains GC at adesired temperature. For drying substrates 104 in the form of the disks120 made from aluminum and having a diameter of about 95 mm and athickness of about 0.80 mm., for example, the heated nitrogen gas 160,for example, may be maintained at a temperature in a range from abouteighty to one hundred degrees C., and may preferably be maintained atabout ninety degrees C. as measured by the gas sensor 350. The preferredideal temperature will depend on the temperature of the fluid 192 at thetop fluid surface 196, which as described below, is about eighty-fivedegrees C. The gas temperature measured by the gas sensor 350 should beabove the temperature of the fluid 192 at the top fluid surface 196, andmay be in the range of from about one to twenty degrees C. in excess ofthe temperature of the fluid 192 at the top fluid surface 196.Preferably the amount of the excess is about ten degrees C., but shouldnot be so high as to cause the fluid 192 at the top surface 196 to boil.

For the same substrates 104, the wall heater 232 may be maintained at atemperature in the range of about eighty to one hundred fifty degreesC., and preferably at about one hundred ten degrees C. As anotherexample, for the ninety degree C. gas curtain temperature measured bythe sensor 350, the temperature of the gas output from the gas heater346 may be about one hundred seventy degrees C.

The controller 340 also provides a control signal 352 to the variablespeed fan 174 that is connected to the exhaust manifold 170. In responseto an output signal 354 from a relative humidity sensor 356 positionedabout one inch above the bottom 168 of the chamber 144, the controller340 adjusts the speed of the fan 174, which increases or decreases therelative humidity. For example, the relative humidity may be controlledso as to be in a range of from about less than forty percent. A thirtypercent relative humidity is preferred for the above-described disks120, for example.

The controller 340 may also control the flow of the gas 160 byregulating an output valve 353 attached to the gas tank 348. Insubstrate drying operations, the gas flow may be in the range of one toten cubic feet per minute (CFM), with a rate of five CFM being preferredfor a chamber 144 used to dry four batches 102 (e.g., the exemplary onehundred) of the above-described disks 120 in one operational cycle.Preliminary to an actual drying operation, for example when the batches102 of substrates 104 are being introduced to the chamber 144 and movedinto the bath 194, the controller 340 may decrease the gas flow rate tothe lower end of that range so that the gas curtains GC will not causethe upper surface 196 of the liquid 192 in the bath 194 to splash orotherwise be disturbed. In this manner, the amount and location of theliquid 192 applied to the opposite sides 124 or 132 of the substrates104 will be controlled by controlling the rate of movement of thebatches 102 of substrates 104 into the bath 194.

The controller 340 may also control the flow rate of the liquid 192 intothe bath 194. For this purpose, the controller 340 may send a signal 361to a pump 360 that receives recirculated liquid 192 from therecirculating drains 222, and supplies the liquid 192 to a liquid heater362 and to a filter 364. The filter 364 may be a 0.05 micron PTFE filtermade by Pall Corporation, for example. Such filter 364 is designed toleave in the filtered liquid 192 only five 710.03 micron particles percubic centimeter of filtered liquid. In response to an output signal 366from a temperature sensor 368 attached to the recirculating drain 222,the controller 340 provides a signal 367 to the liquid heater 362 tomaintain the liquid 192 in the bath 194 in the range of about eighty toeighty-five degrees C. Preferably, the temperature of the liquid 192sensed by the sensor 368 is about eighty-five degrees C. Also, thepreferred temperature at the top fluid surface 196 is about eighty-fivedegrees C.

The controller 340 may also control the operation of the pneumatic motor234 that opens and closes the doors 140. At the start of an operationaldrying cycle, by a signal 376 the controller 340 causes the motor 234 tomove the piston rod 240 to the right as viewed in FIG. 6A to open thedoors 140. When the servo motor 332 has caused the carrier 106 toposition the batches 102 of substrates 104 below the doors 140, thefeedback signal 342 from the servo motor 332 to the controller 340causes the controller 340 to actuate the motor 234 to close the door140. At the end of the drying cycle, when the carrier 106 has beenpositioned in the chamber 144 just below the doors 140, the feedbacksignal 342 is provided from the servo motor 332 to the controller 340.In response, the controller 340 generates the signal 376 to cause themotor 234 to open the doors 140.

Another function of the controller 340 is to activate an anti-staticdevice 373 that creates a charge at the points at which the nitrogen gas160 is introduced into the inlets 150 to prevent static charge fromexisting in the chamber 144.

Yet another function of the controller 340 is to provide the operatingsignals 334 to the servo motor 332 for moving the carrier 106 and thebatches 102 of substrates 104. At the beginning of an operational dryingcycle, after the doors 140 are open, the controller 340 receives thefeedback signal 342 from the servo motor 332 indicating that the arm 112is up, out of the chamber 144. The controller 340 then causes the servomotor 332 to lower the carrier 106 and the substrates 104 into thechamber 144 and then into the bath 194 to the deep immersion depth. Theservo motor sends the signals 342 to the controller 340 when thecarriers 106 have moved lower than the doors 140. In response, thecontroller 340 causes the motor 234 to close the doors 140. The servomotor 332 sends the signals 342 when the deep immersion depth has beenreached, and in response the controller 340 sends the signal 334 causingthe servo motor 332 to stop. The controller 340 may then cause the servomotor 332 to pull the carrier 106 upwardly in the bath 194 and in thechamber 144, and eventually out of the chamber 144 in coordination withoperation of the doors 140.

FIG. 14 shows a flow chart depicting a process of drying batches 102 ofthe substrates 104 according to the present invention. The processstarts with a first operation 374 in which steady-state processconditions are established. In detail, the controller 340 is programmedto set up the process conditions described above. These include: (1) theflow, temperature and monitoring of the nitrogen temperature, (2) theflow, heating and monitoring of the fluid temperature, (3) operation ofthe heaters 232 for the walls 146 and 148, (4) turning on the sensors350, 356, 368, 370, for example, to monitor appropriate conditions, (5)monitoring the relative humidity, and (6) operating the fan 174.

With the steady-state process conditions established, an operation 380is performed. The controller 340 sends the signal 376 to the motor 234to cause the motor 234 to open the doors 140. The batches 102 ofsubstrates 104 have been loaded into the carriers 106 and the carriers106 have been loaded onto the fingers 110. The nitrogen valve 353 is setby a signal 378 from the controller 340 to provide the low gas flow ratedescribed above. The controller 340 then causes the servo motor 332 tolower the carrier 106 and the batches 102 of substrates 104 into thechamber 144. The servo motor 332 sends the signal 342 to the controller340 indicating that the carrier 106 and the batches 102 are completelyin the chamber 144, past the doors 140. The controller 340 then causesthe motor 234 to close the doors 144.

FIG. 15A shows the substrates 104 in the process of being submerged tothe deep immersion position, or depth. When the substrates 104 have beenfully submerged in the fluid 192, the servo motor 332 sends the signal342 to the controller 340, and in response via the valve 353 thecontroller causes the gas flow rate to be increased to the preferredamount for drying. The controller 340 also causes the servo motor 332 tomove the batches 102 of substrates 104 to the deep immersion depth,which is at least one inch below the top surface 196 of the fluid in thebath 194, and depending on the sizes of the bath 194 and the substrate104 may be up to two inches below the top surface 196.

In an operation 381, the servo motor 332 sends the signal 342 to thecontroller 340 indicating that the batches 102 of substrates 104 are atthe deep immersion depth. In response, the controller 340 causes theservo motor 332 to stop, or dwell. At the deep immersion depth, theplanar sides 124 or 132 and the edges 128 or 136 of the substrates 104are now not only wet in a uniform manner, but wet by the very clean,filtered and heated fluid 192. The substrates 104 receive thermal energyfrom the fluid 192. The dwell time at the deep submergence depth isabout from ten to thirty seconds. The dwell time should be long enoughto allow the fluid 192 in the bath 194 to flow over the substrates 104and remove any particles (not shown) remaining on the substrates 104 forcollection by the filter 364 and to allow the temperature of thesubstrates 104 to increase as desired to condition the substrates 104for being dried. By the end of the dwell time the temperatures of theopposite sides 124 or 132 of the substrates 104 increase to about thetemperature of the fluid 192, such as at the top surface 196. Suchtemperature is described above as being about eighty-five degrees C.,and conditions the substrates 104 for being dried as the substrates 104exit the bath 194.

FIG. 15B shows that at the end of the dwell time, operation 383 isperformed by the controller 340 sending the signal 334 to cause theservo motor 332 to transit the carrier 106 and the batches 102 ofsubstrates 104 upwardly in the bath 194 to the shallow immersion depth,which is just under the top surface 196. The time period of this transitis about less than one second to about two seconds. The transit to theshallow immersion depth decreases the overall time required for thedrying process since the subsequent substrate pull operation does nothave to move the substrates 104 from the deep immersion depth, butinstead immediately starts to remove the substrates 104 from the fluid192 into the chamber 144.

When the substrates 104 arrive at the shallow immersion depth, the servomotor 332 sends the signal 342 to the controller 340, and in response,operation 384 is performed. Initially, to establish proper conditionsfor pulling the substrates 104 out of the fluid 192, the controller 340sends the signal 361 to the fluid pump 360 to stop the pump. With thepump 360 stopped, there is no re-circulation of the fluid, such that thetop fluid surface 196 becomes very smooth, or glass-like. Further, thecontroller 340 continues to monitor the temperature and relativehumidity conditions in the chamber 144, and to make the above-describedadjustments as may be necessary.

FIG. 15C shows that in operation 384, the controller 340 causes theservo motor 332 to pull the batches 102 of substrates 104 from the bath194 at a constant rate in the range of about 0.5 to 2.5 mm per second,for example. FIGS. 15C, 16A, and 16B show that the pull at the constantrate results in an increasingly large portion 386 of the substrates 104being out of the fluid 192. The now-very smooth top fluid surface 196through which the substrates 104 are pulled on the way out of the fluid192 promotes formation of a meniscus 388 (shown in FIG. 16A by crosshatching between two lines) between the top fluid surface 196 and eachof the opposite planar sides 124 or 132 of each substrate 104. Themeniscus 388 extends upwardly from the upper surface 196 and is ineffect a localized vertically extending minute section of the fluid 192located above the upper surface 196. The meniscus 388 terminates at arounded nose 390 (FIG. 16B). The meniscus 388 may extend about less thanone mm. from the top fluid surface 196 to the nose 390. Additionally, asthe substrates 104 are pulled upwardly through the smooth top fluidsurface 196 and become separated from the fluid 192, a thin film, ormonolayer, 392 of the fluid 192 forms on each side 124 or 132 of eachsubstrate 104 above the meniscus 388. The thin film 392 may be fromabout 0.5 mm. to 0.005 mm. in height from the nose 390 to a point 393(FIG. 16A) of complete evaporation of the thin film 292, for example.Generally, the thin film 392 may exist only during a very brief timeperiod (e.g., from about 0.001 seconds to about 0.6 seconds) before itevaporates under the steady-state conditions established and maintainedin the chamber 144. The formation of the meniscus 388, and the resultingthin film 392 retained on each side 124 or 132 of each substrate 104,and the very rapid evaporation of the thin film 392 from each side 124or 132 of each substrate 104, are desirable. In particular, the thinfilm 392 on each side 124 or 132 is of uniform thickness, the fluid 192composing the thin film 392 is very clean, and the thin film 392 isremoved by the very rapid evaporation, which promotes the efficientremoval of the thin film 392 according to the present invention, leavingno stains of other marks from drying of the fluid 192.

To increase the number of substrates 104 that may be processed per hourusing the apparatus 100 and method of the present invention, a rate ofupward movement of the servo motor 332 may be selected over a range offrom about 48 mm. to 200 mm. per minute. This rate of movement isselected according to the characteristics of the (a) substrates 104 thatare to be carried in the carrier 106, and (b) fluid 192 in the bath 194.More particularly, for each combination of substrates 104 and fluid 192,there is maximum rate of movement of the substrates 104 out of the bath194 at which the eniscus 388 and the thin film 392 of fluid 192 willform on each side 124 or 132 of the substrates 104. It is undesirablefor the servo motor 332 to move the carrier 106 out of the bath 194 at arate greater than this maximum rate of movement of the substrates 104out of the bath 194. In detail, if this rate is exceeded, then themeniscus 388 and the thin film 392 will become discontinuous. Thediscontinuous meniscus and thin film 392 do not uniformly wet each side124 or 132 of the substrates 104, such that undesirable uneven dryingand staining of the sides 124 or 132 may occur.

Referring to FIG. 16A, it may be understood that above the thin film 132on each side 124 or 132 of each substrate 104 the substrate is dry. Thecontroller 340 continues to monitor the signals 354 from the relativehumidity sensor 356, and to control the speed of the fan 174 to avoidrecondensation of the vaporized fluid 176. FIGS. 7 and 9D show that theeffect of excessively high relative humidity (e.g., promotingrecondensation of the vaporized fluid 176 onto the dried substrates 104)is avoided by controlling the operational speed of the exhaust fan 174to draw the fluid-vapor-laden gas 160 (the gas 160 and the vapor 176from the evaporated fluid 192) from the volume adjacent to the bottom168 of the chamber 144 where the substrates 104 are still initiallybeing dried and to draw any liquid vapor 298 directly into the gasoutlet 162. The relative humidity in the chamber 144 is controlled bythe speed of the fan 174 to provide the above-described preferredrelative humidity, to avoid such recondensation, and to avoidcondensation of such vapor 298 on the substrates 104.

FIG. 15D shows that at the end of the pull of operation 384, the carrier106 is positioned in the chamber 144 just below the doors 140. At thistime, operation 394 is performed. In operation 394, the servo motor 332outputs the signal 342 to the controller 340. In response, thecontroller 340 sends the signal 334 to cause the servo motor 332 tostop, or dwell. The duration of the dwell adjacent to the closed doors140 may vary from zero to fifteen seconds, depending on the nature ofthe fluid 192, for example. When the fluid 192 is de-ionized heatedwater, for example, the duration of the dwell may be very short (e.g.,zero or a mere pause to allow the doors 140 to be opened). In the caseof fluids 192 other than de-ionized water a longer dwell period may beused. If it is determined that the particular fluid 192 has not driedfrom the carrier 106 during the drying cycle, such that by the time thecarrier 106 arrives below the closed doors 140 at the end of operation384 the carrier 106 is still wet with the fluid 192, then the durationof the dwell at the doors 140 may be adjusted to assure that no drops ofthe fluid 192 are on the carrier 106 before the doors 140 are opened.

Following the desired duration of the dwell, the controller 340 sendsthe signal 376 to the motor 234 to cause the motor 234 to open the doors140. The controller 340 also sends the signal 334 causing the servomotor 332 to pull the carrier 106 and the dried substrates 104completely from the chamber 144, at which time the substrate dryingprocess is done.

Efficient removal of the fluid 192 from the substrates 104 is achievedby the transfer of thermal energy to the substrates 104 and to the thinfilm 392 of fluid 192 as the substrates 104 and the bath 194 areseparated. An initial input of thermal energy to the substrates 104 isfrom the heated fluid 192. A further input of thermal energy to thesubstrates 104, and to the thin films 392 on the substrates 104, is fromthe heated gas 160 flowing in the chamber 144. FIG. 13 shows that thegas 160 receives thermal energy from the gas heater 346. A further inputof thermal energy to the substrates 104, and to the thin films 392, isfrom the walls 146 and 148 of the chamber 144. FIG. 9D shows that thewalls 146 of the chamber 144 are provided with the flat heaters 232, andthe walls 148 are provided with the flat heaters 232 in a similarmanner. With the walls 146 and 148 at the temperature described above,the gas 160 flowing in the flow curtains GC may contact the walls 146and 148 and receive thermal energy. With the walls 146 and 148 at theselected temperature, the walls 146 and 148 also transfer radiantthermal energy to the substrates 104 and to the thin films of fluid 392on the substrates 104 as the substrates 104 are pulled from the bath 194into and through the chamber 144. The radiant thermal energy helpsassure that the temperature of the substrates 104 and of the thin films392 does not decrease as the substrates 104 are moved from the bath 194into and through the chamber 144

As noted, prior to the present invention, there was a need for apparatusand methods of efficiently drying the substrates 104. The efficientdrying resulting from use of the present invention allows the substrates104 to be separated from the fluid 192 at the described selected ratewhich is no less than the maximum rate at which a meniscus 388 will formbetween the fluid 192 and the sides 112 of the substrates 104. As aresult, the overall period of time taken in the typical drying cycledescribed with respect to FIG. 14 may not exceed about two minutes. Tonot exceed such time period, the drying cycle rapidly removes from thesubstrates 104 the thin films 392 of the fluid 192 that are uniformlyformed on the substrates 104 as the substrates 104 and the bath 194 areseparated. As described above, “rapidly” means that such removal occursin less than a second as the substrates 104 are pulled from the fluid192.

In review, then, the present invention fills these needs by providingthe apparatus 100 and the described methods of efficiently removing thefluid 192 from the substrates 104. The efficient removing uniformly wetsthe substrates 104 in the fluid 192 so that a consistent startingcondition of the substrates 104 is provided regardless of the type ofprior processing of the substrates 104. In addition, the efficientremoving is attained by defining a gas-filled volume, which is providedby the hot chamber 144 that continuously transfers thermal energy to thesubstrates 104. The substrates 104 and the bath 194 are separated at thecontrolled rate to form the thin films 392 of fluid 192 on thesubstrates 104 as the substrates 104 are positioned in the chamber 144.Further, the hot gas 160 directed into the chamber 160 and across thesubstrates 104 and out of the chamber 144 continuously transfers thermalenergy to the substrates 104. Since the fluid 192 is not drained fromthe bath 194 to enable flow of the gas 160 from the chamber 144, forexample, the directing of the hot gas 160 out of the chamber 144 is notonly continuous, but independent of the separation of the bath 194 andthe substrates 104. With the thin films 392 formed uniformly on theplanar sides 124 and 132, and with the thin films 392 provided withthermal energy as the substrates 104 move up in the chamber 144, thethermal energy transferred to the substrates 104 rapidly evaporates thethin films 392 without decreasing the rate of pull of the substrates 104below the maximum rate at which the meniscus 388 will form. Suchefficient removing is also promoted by controlling the relative humidityin the chamber 144, as controlled by the speed of the fan 174. Theabove-described preferred relative humidity inhibits recondensation ofthe evaporated thin films 392 and condensation of vapor from the bath194 onto the substrates 104.

As described, such efficient removal enables the substrate throughput ofsuch apparatus 100 and method to be limited only by the type ofsubstrates 104 that are being dried, and the type of fluid 192 used towet the substrates 104. Thus, reliance is not placed on the thermalenergy stored in a given substrate 104 to provide all of the thermalenergy necessary to evaporate liquid 192 from the substrates 104.Therefore, the described problems with the prior art dryers are avoided.

Although the foregoing invention has been described in some detail forpurposes of clarity of understanding, it will be apparent that certainchanges and modifications may be practiced within the scope of theappended claims. Accordingly, the present embodiments are to beconsidered as illustrative and not restrictive, and the invention is notto be limited to the details given herein, but may be modified withinthe scope and equivalents of the appended claims.

What is claimed is:
 1. A system for drying batches of disks, comprising:an elongated bath enclosure configured to hold fluid, the fluid defininga top fluid surface, the elongated bath enclosure having an upper enddefined by a weir having a saw-toothed configuration; and a temperatureand humidity-controlled chamber defined above the upper end, the chamberbeing elongated corresponding to the elongation of the elongated bathand having one or more walls, the chamber having a series of firstopenings along the one or more walls at a first location adjacent to theupper end and opposed second openings at a second location that isspaced from the upper end.
 2. A system according to claim 1, furthercomprising: the one or more walls of the chamber extending away from theupper end from the first location to the second location; and a heaterfor maintaining the one or more walls at a selected temperature so as totransfer thermal energy into the chamber between the first location andthe second location.
 3. A system according to claim 1, furthercomprising: a hot gas supply connected to the second openings forcausing a flow of hot gas from the second location through the chambertoward the first location, away from the top fluid surface, and out ofthe first openings.
 4. A system according to claim 3, furthercomprising: a variable speed fan connected to the first openings fordrawing the flow of hot gas from the chamber; and a controllerresponsive to the relative humidity in the chamber for controlling thespeed of the fan.
 5. A system according to claim 1, wherein the diskshave opposite planar sides that are parallel to a planar axis; thesystem further comprising: a disk transport unit for immersing aplurality of batches of disks in the fluid with the planar axis of eachdisk generally perpendicular to the fluid surface and the oppositeplanar sides of each disk generally perpendicular to the one or morewalls; and a drive for causing the disk transport unit to move thebatches of disks within and out of the fluid with the planar axisremaining generally perpendicular to the fluid surface, the drivecontrolling the rate of movement of the batches of disks according tothe location of the batches of disks within and out of the fluid.
 6. Asystem according to claim 5, the system further comprising: a heattransfer unit attached to the one or more walls for transferring thermalenergy to portions of the disks that are out of the fluid as the disksare moved at a controlled rate from the fluid into the chamber.
 7. Asystem according to claim 6, further comprising: a hot gas supplyconnected to each of the opposed second openings for flowing hot gas ina plurality of opposed curtains through the chamber and across theportion of each of the opposite planar sides of the disks and out of thechamber through the first openings to continuously transfer thermalenergy at a selected temperature to the portion of each opposite planarside of the disk and to a thin layer of fluid that forms on each portionas the disks move out of the fluid.
 8. A system according to claim 1,further comprising: a disk transport unit for simultaneously immersing aplurality of batches of disks in and removing the batches of disks fromthe fluid; a drive for causing the disk transport unit to simultaneouslymove the batches of disks within and out of the fluid; and a controllerfor causing the drive to simultaneously move the batches of disks atrates of movement controlled according to the location of the batches ofdisks within and out of the fluid.
 9. A system according to claim 8,wherein one of the controlled rates of movement is a substantiallyconstant rate of movement of the batches of disks out of the fluid toform a thin film of fluid on opposite planar sides of a portion of eachdisk just exiting the fluid.
 10. A system according to claim 8, furthercomprising: the controller causing the drive to immerse the batches ofdisks in the fluid and move the batches of the disks to a deep immersiondepth below the top fluid surface.
 11. A system according to claim 8,further comprising: the controller causing the drive to hold the batchesof disks immersed in the fluid at a deep immersion depth below the topfluid surface for a predetermined period of time, and then to rapidlymove the batches of disks to a shallow immersion depth below andadjacent to the top fluid surface.
 12. A system according to claim 8,further comprising: opposed doors movably mounted adjacent to the secondopenings for opening and closing the chamber; the controller causing thedrive to move the batches of disks through the elongated chamber to alocation adjacent to the opposed doors; and a sensor responsive to thebatches of disks at the location adjacent to the doors for opening thedoors to permit the batches of dried disks to exit the elongatedchamber.
 13. A system according to claim 8, further comprising: a pumpfor recirculating the fluid from and back into the bath; the controllercausing the pump to stop recirculating the fluid; and when the pumpstops recirculating the fluid, the controller being effective to causethe drive to pull the batches of disks at a constant rate of movementout of the fluid to dry the disks.
 14. Apparatus for drying a pluralityof batches of disks, each of the disks having opposite sides, theapparatus comprising: a bath adapted to contain hot liquid, the liquiddefining an upper liquid surface, the bath being elongated tosimultaneously receive the plurality of batches of disks aligned inseries along a batch disk path, the bath having a saw toothed weirdefining an upper end of the bath over which the liquid may flow out ofthe bath; a liquid collection tank surrounding and supporting the bathfor receiving the liquid flowing over the weir, the tank having an upperend above the weir; a drain system connected to the tank forrecirculating the liquid that flows over the weir, the drain systemfiltering, heating and returning the liquid to the bath; an enclosureconfigured to receive the plurality of batches of disks aligned inseries along the batch disk path, the enclosure having opposingelongated walls positioned on opposite sides of the batch disk path, theenclosure having an upper end and a base spaced from the upper end, thewalls being connected to the tank for supporting the tank and the bath;a series of gas inlets defined in each of the opposing elongated wallsat the upper end of the enclosure and spaced above the weir, the inletsextending along the opposing elongated walls on opposite sides of anupper position of the batch disk path; and a gas outlet adjacent to thebase of each of the elongated walls and spaced from the upper liquidsurface; the enclosure and the inlets and the outlets definingcontinuous gas flow paths from the inlets through the enclosure to theoutlets, the flow path extending across the weir for drawing ambientvapor from the bath directly to the outlets.
 15. Apparatus according toclaim 14, further comprising: a disk carrier movable in the bath and inthe enclosure perpendicular to the batch disk path for moving thebatches of disks; and a controller for causing the carrier to move inthe bath and in the enclosure at controlled rates according to thelocation of the carrier relative to the continuous flow paths. 16.Apparatus according to claim 14, further comprising: a disk carriermovable in the bath and in the enclosure perpendicular to the batch diskpath for moving the batches of disks; and a controller for causing thecarrier to move in the bath and in the enclosure at controlled ratesaccording to the location of the carrier relative to the continuous flowpaths.
 17. A system according to claim 16, wherein one of the controlledrates of movement is a substantially constant rate of movement of thebatches of disks out of the liquid to form a thin film of liquid on aportion of the opposite planar sides of each disk as each disk exits theliquid.
 18. A system according to claim 16, further comprising: thecontroller causing the carrier to immerse the batches of disks in theliquid in the bath and move the batches to a deep immersion depth belowthe upper surface of the liquid.
 19. A system according to claim 16,further comprising: the controller causing the carrier to hold thebatches of disks immersed in the liquid at a deep immersion depth belowthe upper liquid surface for a predetermined period of time, and thencausing the carrier to rapidly move the batches of disks to a shallowimmersion depth below and adjacent to the upper liquid surface.
 20. Asystem according to claim 16, further comprising: opposed doors movablymounted at the upper end of the enclosure for opening and closing theenclosure; and the controller causing the carrier to move the batches ofdisks in the enclosure to a location adjacent to the doors; and uponmovement of the batches of disks to the location adjacent to the doorsthe controller causing the doors to open to permit the batches of disksto exit the enclosure.
 21. A system according to claim 16, furthercomprising: a pair of opposed doors mounted at the upper end of theenclosure and being movable together to close the upper end of theenclosure and apart to allow the carrier and the batches of disks toexit the enclosure; the controller causing the carrier with the batchesof disks to move from a first location out of the liquid toward theupper end of the enclosure, and to pause at a second location adjacentto the upper end to position the carrier in the incoming hot gas; and inresponse to the carrier at the second location, the controller causingthe doors to open during the pause.
 22. A system according to claim 16,further comprising: the controller synchronizing the movement of thecarrier in the bath and in the enclosure with the supply of the hot gasto the inlets, the synchronizing reducing the flow of the hot gas as thecarrier moves in the enclosure toward and through the upper liquidsurface.
 23. Apparatus according to claim 14, wherein the disks eachhave opposite planar sides and a narrow edge between the sides, thecarrier further comprising: elongated spaced arms configured to extendin the enclosure parallel to and between the opposing elongated walls;and a disk batch nest corresponding to each batch of the disks, eachnest including a plurality of spaced bars and spaced end plates mountingthe bars on the spaced arms, each of the bars including a verticalsurface intersecting a V-shaped notch corresponding to each disk to becarried, each V-shaped notch being formed in the bar with a valley andopposite walls extending at an acute angle with respect to the verticalsurface, the vertical surface and the acute angle of the V-shaped notchcombining to limit the contact between the disk and each V-shaped notch,the contact being a substantially point contact between one of theopposite walls of the notch and one end of the narrow edge of the disk.24. Apparatus according to claim 14, further comprising: a relativelyshort wall at each end of the opposing elongated walls; the upper end ofthe enclosure comprising an elongated opening defined by the opposingelongated walls and by the relatively short walls, the elongated openingbeing configured to receive the plurality of batches of disks aligned inthe series along the batch disk path; a plurality of doors, each doorhaving first ends adjacent to one of the short walls and opposite secondends adjacent to the other of the short ends; door mounts adjacent toeach of the short walls for guiding the doors across the elongatedopening in opposition to each other; a drive mounted adjacent to one ofthe short walls and connected to the first end of one of the doors; afirst endless belt driven by the drive and connected to thecorresponding first end of the other of the doors so that thecorresponding first ends of the doors move simultaneously on the doormounts; a connecting shaft for each of the doors, the shafts beingdriven by the first endless belt and extending from the one of the shortwalls to the other of the short walls; and a second endless belt drivenby the connecting shafts for moving the opposite corresponding secondends of the doors simultaneously and in synchronism with the movement ofthe corresponding first ends of the doors to open or close the elongatedopening.
 25. A system according to claim 14, further comprising: astandpipe positioned in the liquid collection tank, the standpipe havingan inlet located below the level of weir for draining excess liquid fromthe tank.